The in¯uence of row position and selected soil attributes
on Acarina and Collembola in no-till and conventional
continuous corn on a clay loam soil
C.A. Fox
*, E.J.A. Fonseca, J.J. Miller, A.D. Tomlin
Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, 1391 Sandford St., London, Ont., Canada N5V 4T3
Received 25 July 1998; accepted 20 August 1998
Abstract
Population abundances of both Acarina (mites) and Collembola (springtails) were examined for continuous corn grown under no-till and conventional management practices on a clay loam, an Orthic Humic Gleysol (Typic Haplaquoll) near Ottawa, Ont., Canada (Lat. 458220N; Long. 75
8430W). For each tillage practice, samples for soil faunal extraction and soil attribute
characterization were taken periodically during the growing seasons of 1989 (5 samplings) and 1990 (4 samplings). Each time, samples (0±5 cm depth) were taken every 15 cm across a 1.5 m transect spanning three rows of corn that included both a traf®c and a non-traf®c row in order to assess if population abundances were signi®cantly in¯uenced by soil attributes related to changes in disturbance and compaction due to row position. Row position had a signi®cant effect (analysis of variance based on split±split plot model) on Cryptostigmata in 1989, and in 1990, on Prostigmata, Onychiuridae, and Cryptostigmata. From canonical correlation analysis, for 1989 and 1990, respectively, 71% and 61% of the variation in the biotic data set could be explained by variation in the abiotic data. Crown copyright#1999 Published by Elsevier Science B.V. All rights reserved.
Keywords:Tillage practices; Soil microarthropods; Soil attributes; Canonical correlation analysis
1. Introduction
Various soil environments directly in¯uence the soil microarthropod community with respect to numbers and composition (AndreÂn and LagerloÈf, 1983) and, according to Farrar and Crossley (1983), their spatial distribution. The in¯uence on soil organism popula-tions is expected to be most evident when conservation practices such as no-till are implemented on pre-viously conventionally tilled areas because the
reloca-tion of crop residues to the surface in no-till systems will affect the soil decomposer communities (Beare et al., 1992). Microarthropod numbers, speci®cally Acarina (mites) and Collembola (springtails) have been shown to increase with no-till practices when compared to conventional tillage (Hendrix et al., 1986) because the crop residue cover of no-till pro-vides a readily available food source, moderates extremes of surface soil temperatures, reduces moist-ure loss, and in¯uences the predominance of certain organisms (House and Stinner, 1987; Perdue and Crossley, 1989; Beare et al., 1992; Doran and Linn, 1994). Under conventional systems, with moldboard
Applied Soil Ecology 13 (1999) 1±8
*Corresponding author. Tel.: 457-1470; fax: +1-519-457-3997; e-mail: foxc@em.agr.ca
plowing and disking, microarthropod numbers can be reduced as a result of exposure to desiccation, destruc-tion of habitat and disrupdestruc-tion of access to food sources (House and Alzugaray, 1989). The in¯uence of these impacts on the abundance of soil organisms will be either moderated or intensi®ed depending on their spatial location; that is, in-row where plants are grow-ing, near the row where residues accumulate or between rows being subjected to possible compaction from mechanized traf®c.
In a study comparing conventional and no-till til-lage systems on a clay loam with continuous corn cropping, the following objectives were addressed:
1. to determine if the abundance of Acarina and Collembola at different row positions was sig-ni®cantly in¯uenced by soil attributes related to factors of mechanical disturbance and compaction (i.e., bulk density, moisture content) and residue accumulation/decomposition (i.e., % organic car-bon, % nitrogen, pH, exchangeable cations); and 2. to determine to what extent variations in soil fauna
abundances can be accounted for by the variations in soil attributes.
2. Materials and methods
No-till and conventional continuous corn plots were sampled on a clay loam near Ottawa, Ont., Canada (Lat. 458220N; Long. 75
8430W) during two growing seasons, 1989 (5 samplings: June 1 and 3 (post-planting with corn 15±20 cm in height), June 29, July 31, September 6 and October 5) and 1990 (4 sam-plings: April 26 (pre-planting), June 6 (post-planting), August 8, and October 3). The soil is classi®ed as Orthic Humic Gleysol (Agriculture Canada Expert Committee on Soil Survey, 1987) or Typic Haplaquoll (Soil Survey Staff, 1992).
The tillage plots were established in 1988 using a randomized complete block, split plot design with four ®eld replicates (or blocks) of the tillage treatments. Prior to 1987, alfalfa was grown. During 1987, corn (Pioneer 3949) at 65 000 plants haÿ1
was grown under conventional tillage. In 1989 and 1990, corn (Pioneer 3902) was planted at 65 000 plants haÿ1
and 3.1 l haÿ1
(dicamba) were applied. Ammo-nium nitrate (34-0-0) at 172 kg N haÿ1
was broadcast
and phosphorus and potassium (0-20-20) at 60 kg haÿ1
was banded by side dressing at planting. For the conventionally tilled plots, which were Fall plowed and Spring disked each year, all wheel traf®c was maintained during the growing season in the same rows following planting. For the no-till plots, traf®c rows were con®ned to the same rows for each year of the study resulting in a cumulative effect for compac-tion and no disturbance occurred except at planting to insert the seeds. Additional information for 1988± 1989 on root mass distribution, bulk density, and soil moisture is reported in Dwyer et al. (1996).
In 1989, two of the four blocks were sampled; and, in 1990, the study was expanded to include a third block. At each sampling time, adjacent samples for both soil fauna and soil attributes were taken from 0± 5 cm depth, spaced approximately every 15 cm apart across a transect (1.5 m) that spanned 3 rows of corn and included non-traf®c and traf®c row effects. This procedure resulted in 3 samples for each row position (in-row, traf®c, and non-traf®c) at each sampling time during the growing season for each ®eld replicate.
A modi®cation of the Merchant-Crossley extractor as speci®ed by Norton (1985) was used over a two-week time period to extract Acarina and Collembola from intact soil cores. These soil cores were obtained with an aluminum cylinder, 7.5 cm diameter5 cm in length. Reagent grade ethylene glycol (Edwards and Fletcher, 1971) was used to capture the microarthro-pods in 275 ml plastic cups. Acarina were identi®ed to suborder level and Collembola to family level. Addi-tional information from 1988±1989 about abundance and richness of the microarthropod and cryptozoic fauna (large soil invertebrates that live and/or hide on the soil surface) is reported in Neave and Fox (1998). In 1989, the following soil analyses as outlined in Sheldrick (1984) were completed: organic carbon and nitrogen by Leco determination, pH in 0.01 M calcium chloride; permanent charge cation exchange capacity (CEC) and exchangeable cations (Ca, Mg, K) by sodium chloride extractions. In 1990, all soil analyses were repeated except for CEC and exchangeable cations. Soil bulk density was estimated from the intact core obtained for faunal extraction.
Analysis of variance (SAS Institute Inc., 1989) based on a split±split plot model design was used to test for signi®cant interaction of each microarthropod and soil attribute variable with respect to experimental
block design (Block), cultivation (Cult), row location (Loc), and time of sampling (Time). Canonical corre-lation analysis (SAS Institute Inc., 1989) was used to determine the extent of variation in microarthropod population distributions that could be explained by the variation in soil attributes and identify the main interacting variables.
3. Results and discussion
3.1. Effect of specific field factors
For 1989, the main results determined from the analysis of variance for treatment effects and interac-tions for all ®ve sampling events combined (post-planting to harvest) are shown in Table 1. Row loca-tion had a signi®cant in¯uence on the following biotic and abiotic attributes: total Cryptostigmata, total Acarina, total fauna, % organic carbon (wt./vol.), % nitrogen (wt./vol.), bulk density (g/cc), % H2O (wt./ vol.), CEC (cation exchange capacity), and % exchangeable Ca and K (wt./vol.). For Prostigmata and Mesostigmata, there was a signi®cant loca-tioncultivation interaction effect suggesting that compaction in combination with crop residues and tillage were factors in¯uencing abundance. In con-trast, neither cultivation nor a locationcultivation interaction were signi®cant (p> 0.10) in explaining variation in numbers of Cryptostigmata. From these observations, one could infer that for cryptostigmatid numbers, the crop residue cover that had accumulated by 1989, the second year of no-till, was not yet a signi®cant factor to differentiate it from the conven-tionally tilled plot; but rather, Cryptostigmata responded directly to compaction differences (bulk density) in the row. In 1989, compaction differences in the row were clearly evident in the ®eld during the growing season. All of the tillage plots had been severely compacted by wheel traf®c at the time of planting due to wet conditions and for the remaining sampling times all wheel traf®c was con®ned to the same rows. The time of sampling during 1989 (Table 1) had a signi®cant effect on Prostigmata, Astigmata and Cryptostigmata, re¯ecting the varying soil moisture and temperature regimes that occur during the growing season. There was also a signi®-cant timecultivation interaction for Prostigmata,
Mesostigmata, Cryptostigmata, Onychiuridae, Podur-idae, and Sminthuridae indicating that tillage differ-ences in combination with sampling time was also a contributing factor to population abundances. Perdue and Crossley (1989) observed in a sandy clay loam that higher Prostigmata and Oribatei populations responded to increased moisture retention properties under no-till and that sampling period affected varia-tion in numbers.
For 1990 data that included pre-planting, row posi-tion had a signi®cant (p0.10) in¯uence on the fol-lowing: Prostigmata, Cryptostigmata, Onychiuridae, bulk density and % H2O. This further supports the inference drawn from 1989 observations that only certain faunal groups were responding directly to the row position effects of compaction. Onychiuridae were also signi®cantly affected by a location cultiva-tion interaccultiva-tion. When 1990 data were reconsidered for only sampling times following planting, the loca-tioncultivation interaction for Onychiuridae (F17.06, df2.8;p0.0013) remained. In addition, there was no longer a signi®cant row location effect for Cryptostigmata (F2.94; df2.8;p0.1101), but there was a signi®cant (F4.13; df2.8; p0.0585) locationcultivation interaction suggesting that popu-lation numbers sampled after planting were more affected by residue and tillage effects rather than compaction. As was observed for 1989 data, there was again in 1990, a signi®cant effect of sampling time, but for all faunal groups (Table 2) re¯ecting the in¯uence of seasonal changes in moisture.
3.2. Extent of variation between abiotic and biotic data sets
In 1989, for the ®rst canonical components (Fig. 1(a)), 40% (p0.0001) of the variation between the abiotic and biotic data set could be attributed to the following main in¯uencing variables: % H2O, pH and numbers of Astigmata, Sminthuridae, and Mesostig-mata. The effect of seasonal sampling time on the observations is shown in Fig. 1(a) with a distinct separation of the June 1 and 3 sampling. For 1990, for the ®rst canonical components (Fig. 1(b)), 33% (p0.0001) of the variation was explained by % H2O, % organic carbon, and number of Astigmata, Ony-chiuridae, Entomobryidae, and Cryptostigmata. Separation amongst seasonal sampling times was less
Table 1
Analysis of variance (SAS/STAT1) summary of significant
p-values for 1989 data (post-plant to harvest)a
Biotic/abiotic attribute Whole plotBlockCult (df1)
Split plotBlockLoc(Cult) (df4)
Split±split plotBlockTime(Cult Loc) (df24)
Block (df1)
Cult (df1)
Loc (df2)
LocCult (df2)
Time (df4)
TimeCult (df4)
TimeLoc (df8)
TimeLocCult (df4)
Total Acarina 0.037 0.015 0.0001 0.096
Total Collembola 0.0095
Total Fauna 0.068 0.038 0.0001 0.068
Prostigmata 0.0003 0.0001 0.040 0.051
Mesostigmata 0.087 0.026
Astigmata 0.0001
Cryptostigmata 0.014 0.0011 0.072
Onychiuridae 0.096 0.032
Poduridae 0.072
Isotomidae 0.039
Entomobryidae
Sminthuridae 0.003 0.061
% Carbon (wt./vol.) 0.084 0.037 0.0026 0.072 0.052
% Nitrogen (wt./vol.) 0.047 0.026 0.045 0.060 0.079
Bulk density (g/cc) 0.094 0.011 0.0008 0.080
% H2O (wt./vol.) 0.018 0.0001 0.054
CEC meq/100 g 0.060 0.080 0.0030 0.0010 0.012 % Exchangeable Ca (wt./vol.) 0.0009 0.0031 0.045 % Exchangeable K (wt./vol.) 0.066 0.070 % Exchangeable Mg (wt./vol.)
aSignificance levels forp0.10; Block ± field replicate; Cult ± cultivation; Loc ± row position; Time ± sampling event.
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Table 2
Analysis of variance (SAS/STAT1) summary of significant
p-values for 1990 data (pre-plant to harvest)a
Biotic/abiotic attribute Whole plotBlockCult (df2)
Split plotBlockLoc(Cult) (df8)
Split±split plotBlockTime (Cult Loc) (df36)
Block (df2)
Cult (df1)
Loc (df2)
LocCult (df2)
Time (df3)
TimeCult (df3)
TimeLoc (df6)
TimeLocCult (df6) Total Acarina 0.073 0.014 0.023 0.0001
Total Collembola 0.0001 0.0001
Total Fauna 0.059 0.022 0.020 0.0001
Prostigmata 0.020 0.0001 0.001
Mesostigmata 0.0003
Astigmata 0.0001
Cryptostigmata 0.097 0.005
Onychiuridae 0.019 0.005 0.0001 0.0007
Poduridae 0.0001 0.0005
Isotomidae 0.082 0.0005 0.011
Entomobryidae 0.0001
Sminthuridae 0.0001 0.0001
% Carbon (wt./vol.) 0.023 % Nitrogen (wt./vol.) 0.034
Bulk Density (g/cc) 0.090 0.024
% H2O (wt./vol.) 0.018 0.023 0.037 0.0001 aSignificance levels forp0.10; Block ± field replicate; Cult ± cultivation; Loc ± row position; Time ± sampling event.
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pronounced for 1990 (Fig. 1(b)) than for 1989; but for April 26 (moist conditions) and August 8 (dry), there was a more de®ned grouping of observations. For the ®rst canonical components for both 1989 and 1990, the variation between the biotic and abiotic data set
can be related to the seasonal moisture in¯uences on the particular faunal groups.
The second canonical components for 1989 (Fig. 1(c)) explained an additional 31% (p0.0001) of the variation between the abiotic and biotic data set
Fig. 1. Results of canonical correlation analysis of abiotic and biotic attributes showing as follows: interacting factors for first canonical components, CC1, for (a) 1989 and (b) 1990 with respect to sampling time; interacting factors for second canonical components, CC2, for (c) 1989 and (d) 1990 with respect to cultivation and (e) 1989 and (f) 1990 with respect to row position. Conv-till refers to conventional tillage with plowing and disking and No-till refers to no-till tillage where no mechanical disturbance is undertaken except for seeding.
with % H2O, % organic carbon, bulk density, % exchangeable Mg, and numbers of Sminthuridae, Astigmata, Cryptostigmata, and Entomobryidae as the main interacting variables. For 1990 (Fig. 1(d)), for the abiotic and biotic data sets, the second cano-nical components explained an additional 28% (p0.0001). The main in¯uencing factors were % H2O, % organic carbon, bulk density and numbers of Mesostigmata, Cryptostigmata, Astigmata, and Poduridae. When the observations were identi®ed with respect to cultivation (Fig. 1(c) and (d)), there was a distinct separation between no-till and conven-tional tilled systems for 1990. In contrast, 1989 showed no separation suggesting that not until the third year following no-till implementation was the variation amongst the soil abiotic and biotic attributes suf®cient to uniquely separate the tillage systems. When the observations for both 1989 and 1990 were identi®ed by row position (Fig. 1(e) and (f)), there was a slight tendency for separation of the observations related to traf®c rows suggesting the in¯uence of compaction on the variation between the biotic and abiotic data set. The variation explained by the second canonical components can be interpreted as being related to the tillage in¯uences on both the soil attributes and particular faunal groups.
For this study, a signi®cant 71% and 61% of the variation in the biotic data could be explained by the variation in the abiotic data for 1989 and 1990, respectively. This study also con®rms other ®ndings that tillage practices and the corresponding soil con-ditions have a signi®cant in¯uence on population abundances of Acarina and Collembola. Identifying the main in¯uencing variables provides a valuable step towards undertaking further research to understand the spatial relationships of soil fauna and soil properties across a ®eld and possibly at landscape scales as agronomic practices become implemented. In the short-term, implementing tillage systems such as establishing no-till on areas previously under conven-tional tillage will lead to soil ecological changes with unique response times amongst the biotic and abiotic attributes. Whether these same interacting biotic and abiotic attributes continue over the long-term in response to the amount of disturbance, compaction and residue incorporation is the basis for further research to determine the progression of change whether negative, positive or stable with time.
Acknowledgements
The authors are grateful to the following Agricul-ture and Agri-Food Canada colleagues who helped us undertake this study: J.L.B. Culley and M. McGovern for initiating and maintaining the tillage experiment, V. Behan-Pelletier for helpful discussions on soil fauna methodology; G. Butler and G. Umphrey for their advice on analysis of variance procedures.
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